Described herein is a process for the fabrication of an electronic device. More specifically, described herein are compositions for forming a silicon-containing film in a deposition process, such as, without limitation, a flowable chemical vapor deposition. Exemplary silicon-containing films that can be deposited using the compositions and methods described herein include, without limitation, silicon oxide, silicon nitride, silicon oxynitride or carbon-doped silicon oxide or carbon-doped silicon nitride films.
Flowable oxide deposition methods typically use alkoxysilane compounds are as precursors for silicon-containing films which are deposited by controlled hydrolysis and condensation reactions. Such films can be deposited onto a substrate, for example, by applying a mixture of water and alkoxysilanes, optionally with solvent and/or other additives such as surfactants and porogens, onto a substrate. Typical methods for the application of these mixtures include, without limitation, spin coating, dip coating, spray coating, screen printing, co-condensation, and ink jet printing. After application to the substrate and upon application of one or more energy sources such as, without limitation thermal, plasma, and/or other sources, the water within the mixture can react with the alkoxysilanes to hydrolyze the alkoxide and/or aryloxide groups and generate silanol species, which further condense with other hydrolyzed molecules and form an oligomeric or network structure.
Besides physical deposition or application of the precursor to the substrate, vapor deposition processes using water and a silicon containing vapor source for flowable dielectric deposition (FCVD) have been described, for instance, in U.S. Pat. Nos. 8,481,403; 8,580,697; 8,685,867; US Publ. No. 2013/0230987 A1; U.S. Pat. Nos. 7,498,273; 7,074,690; 7,582,555; 7,888,233; and 7,915,131. Typical methods generally relate to filling gaps on substrates with a solid dielectric material by forming a flowable film in the gap. The flowable film is formed by reacting a dielectric precursor which may have a Si—C bond with an oxidant to form the dielectric material. In certain embodiments, the dielectric precursor condenses and subsequently reacts with the oxidant to form dielectric material. In certain embodiments, vapor phase reactants react to form a condensed flowable film. Since the Si—C bond is relatively inert towards reaction with water, the resultant network may be beneficially functionalized with organic functional groups which impart desired chemical and physical properties to the resultant film. For example, the addition of carbon to the network may lower the dielectric constant of the resultant film.
Another approach to depositing a silicon oxide film using flowable chemical vapor deposition process is gas phase polymerization. For example, the prior art has focused on using compounds such as trisilylamine (TSA) to deposit Si, H, N containing oligomers that are subsequently oxidized to SiOx films using ozone exposure. Examples of such approaches include: U. S. Publ. No. 2014/073144; U. S. Publ. No. 2013/230987; U.S. Pat. No. 7,521,378, U.S. Pat. No. 7,557,420, and U.S. Pat. No. 8,575,040; and U.S. Pat. No. 7,825,040.
The reference article “Novel Flowable CVD Process Technology for sub-20 nm Interlayer Dielectric”, H. Kim et al., Interconnect Technology Conference (IITC), 2012 IEEE International, San Jose, Calif. describes a flowable CVD process using remote plasma during low temperature deposition and ozone treatment to stabilize the film. Also described in the reference was a flowable CVD process which does not oxidize Si or electrode, resulted in removal of Si3N4 stopper layer as an oxidation or diffusion barrier. After the application of Flowable CVD to 20 nm DRAM ILD, the authors could reduce not only loading capacitance of Bit-line by 15% but also enhance comparable productivity. Through the successful development of sub-20 nm DRAM ILD Gap-fill process, Flowable CVD was successful demonstrated as a promising candidate for mass production-worthy ILD in sub-20 nm next generation devices.
Despite the recent activity in the art related to flowable chemical vapor deposition and other film deposition processes, problems still remain. One of these problems is related to film composition. For example, flowable oxide films deposited from the precursor trisilylamine (TSA) in a gas phase polymerization process yield films with a high density of Si—H bonds and have a wet etch rates in dilute HF solutions that are 2.2 to 2.5 times faster than high quality thermal oxide. Thus, there is a need to provide alternative precursor compounds to produce silicon-containing films with a lower Si—H bond density, a lower film etch rates, or a combination thereof.